Combination structures and optical filters and image sensors and camera modules and electronic devices

ABSTRACT

A combination structure includes an in-plane pattern of unit cells, wherein the each unit cell includes nanostructures each having a dimension that is smaller than a near-infrared wavelength and a light-absorbing layer adjacent to the nanostructures and including a near-infrared absorbing material configured to absorb light in at least a portion of a near-infrared wavelength spectrum. The nanostructures are define a nanostructure array in the unit cells, and a wavelength width at 50% transmittance of a transmission spectrum in the near-infrared wavelength spectrum of the combination structure is wider than a wavelength width at 50% transmittance of a transmission spectrum in the near-infrared wavelength spectrum of the nanostructure array.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of, under 35 U.S.C.§ 119, Korean Patent Application No. 10-2019-0109005 filed in the KoreanIntellectual Property Office on Sep. 3, 2019, the entire contents ofwhich are incorporated herein by reference.

BACKGROUND 1. Field

Combination structures, optical filters, image sensors, camera modules,and electronic devices are disclosed.

2. Description of the Related Art

Electronic devices including image sensors that store an image as anelectrical signal, such as a cell phone, a digital camera, a camcorder,or a camera, have been used.

These electronic devices may include an optical filter in order toreduce or prevent an optical distortion by light in the other regions(e.g., other wavelength spectra) than a visible wavelength spectrum orimprove visibility by light in the other wavelength spectra than avisible wavelength spectrum.

SUMMARY

Some example embodiments provide a combination structure capable ofachieving desired optical properties for light except for visiblewavelength regions (“wavelength regions” or “regions” being referred tointerchangeably herein as “wavelength spectra”) with a thin thickness.

Some example embodiments provide an optical filter including thecombination structure.

Some example embodiments provide an image sensor including thecombination structure or the optical filter.

Some example embodiments provide a camera module including thecombination structure, the optical filter or the image sensor.

Some example embodiments provide an electronic device including thecombination structure, the optical filter, the image sensor, or thecamera module.

According to some example embodiments, a combination structure mayinclude an in-plane pattern of unit cells, wherein each unit cell of theunit cells includes nanostructures each having a dimension that issmaller than a near-infrared wavelength, and a light-absorbing layeradjacent to the nanostructures, the light-absorbing layer including anear-infrared absorbing material configured to absorb light in at leasta portion of a near-infrared wavelength spectrum. The nanostructures maydefine a nanostructure array in the unit cells. A wavelength width at50% transmittance of a transmission spectrum in the near-infraredwavelength spectrum of the combination structure may be wider than awavelength width at 50% transmittance of a transmission spectrum in thenear-infrared wavelength spectrum of the nanostructure array.

The transmission spectrum in the near-infrared wavelength spectrum ofthe nanostructure array may have a first local minimum point and asecond local minimum point separated from each other and a first localmaximum point between the first local minimum point and the second localminimum point, and a difference between a transmittance at either thefirst local minimum point or the second local minimum point and atransmittance at the first local maximum point may be greater than about30%.

The transmission spectrum in the near-infrared wavelength spectrum ofthe combination structure may have a third local minimum point and afourth local minimum point separated from each other and a second localmaximum point between the third local minimum point and the fourth localminimum point, and a difference between a transmittance at either thethird local minimum point and the fourth local minimum point and atransmittance at the second local maximum point may be smaller than thedifference between the transmittance at either the first local minimumpoint or the second local minimum point and the transmittance at thefirst local maximum point.

The difference between the transmittance at either the third localminimum point and the fourth local minimum point and the transmittanceat the second local maximum point may be less than about 30%.

The nanostructure array may include a parallel pattern of a firstnanostructure, a second nanostructure, and a third nanostructure, and amagnitude of a gap between the first nanostructure and the secondnanostructure may differ from a magnitude of a gap between the secondnanostructure and the third nanostructure.

The gap between the first nanostructure and the second nanostructure maybe about 1.05 times to about 5 times as large as the gap between thesecond nanostructure and the third nanostructure.

The nanostructure array may include a first nanostructure and a secondnanostructure which are adjacent to each other and a dimension of thefirst nanostructure may be different from a dimension of the secondnanostructure.

A width of the first nanostructure may be about 1.05 times to 5 times aslarge as a width of the second nanostructure.

A thickness of the first nanostructure may be about 1.05 times to 5times as large as a thickness of the second nanostructure.

The unit cells may include a first unit cell and a second unit cellwhich are adjacent to each other, the first unit cell may include afirst nanostructure and a second nanostructure, the second unit cell mayinclude a third nanostructure and a fourth nanostructure, the firstnanostructure, the second nanostructure, the third nanostructure, andthe fourth nanostructure may define a linear sequence of nanostructuresextending in one direction, and a magnitude of a gap between the firstnanostructure and the second nanostructure may differ from a magnitudeof a gap between the second nanostructure and the third nanostructure.

The gap between the first nanostructure and the second nanostructure maybe about 0.2 times to about 0.9 times or about 1.05 times to about 5times as large as a gap between the second nanostructure and the thirdnanostructure.

A wavelength width at the 50% transmittance of the transmission spectrumin the near-infrared wavelength spectrum of the combination structuremay be about 1.2 times to 5 times as large as a wavelength width at the50% transmittance of the transmission spectrum in the near-infraredwavelength spectrum of the nanostructure array.

A wavelength width at the 50% transmittance of the transmission spectrumin the near-infrared wavelength spectrum of the combination structuremay be about 40 nm to about 200 nm.

The light-absorbing layer may be at at least one of a lower surface, anupper surface, and/or one or more side surfaces of one or morenanostructures of the nanostructures.

The nanostructure and the light-absorbing layer may be in contact witheach other.

The near-infrared wavelength may be in a range of greater than about 700nm and less than or equal to about 1200 nm.

The near-infrared wavelength may be in a range of about 890 nm to about990 nm.

The nanostructures may each include a high refractive material having arefractive index of greater than or equal to about 2.0 at a wavelengthof 940 nm.

The nanostructure may each include titanium oxide, silicon, aluminum, aGroup III-V semiconductor compound, or a combination thereof.

A maximum absorption wavelength of the near-infrared absorbing materialmay be in a range of about 890 nm to about 990 nm.

A thickness of the combination structure may be less than or equal toabout 1 μm.

According to some example embodiments, a combination structure mayinclude an in-plane pattern of unit cells. Each unit cell of the unitcells may include two or more nanostructures each having a smallerdimension than a near-infrared wavelength, and a light-absorbing layeradjacent to at least one of a lower surface, an upper surface, and/orone or more side surfaces of one or more nanostructures of the two ormore nanostructures, the light-absorbing layer including a near-infraredabsorbing material configured to absorb light of at least a portion of anear-infrared wavelength spectrum. The unit cells may include a firstunit cell and a second unit cell adjacent to each other. The first unitcell may include a first nanostructure and a second nanostructure. Thesecond unit cell may include a third nanostructure and a fourthnanostructure. The first nanostructure, second nanostructure, thirdnanostructure, and fourth nanostructure may define a linear sequence ofnanostructures extending in one direction. A dimension of the firstnanostructure may be different from a dimension of the secondnanostructure, or a magnitude of a gap between the first nanostructureand the second nanostructure may be different from a magnitude of a gapbetween the second nanostructure and the third nanostructure.

The dimension of the first nanostructure may be different from thedimension of the second nanostructure, and the width of the firstnanostructure may be about 1.05 times to about 5 times as large as thewidth of the second nanostructure.

The gap between the first nanostructure and the second nanostructure maydiffer from the gap between the second nanostructure and the thirdnanostructure, and the gap between the first nanostructure and thesecond nanostructure may be about 0.2 times to about 0.9 times or about1.05 times to about 5 times as large as the gap between the secondnanostructure and the third nanostructure.

According to some example embodiments, an optical filter including thecombination structure is provided.

According to some example embodiments, a camera including the opticalfilter is provided.

According to some example embodiments, an image sensor may include asemiconductor substrate including a plurality of photodiodes and anoptical filter on the semiconductor substrate and configured to blocklight in at least a portion of near-infrared wavelength spectra, whereinthe optical filter includes the combination structure.

The image sensor may further include a color filter on the opticalfilter.

According to some example embodiments, a camera includes the imagesensor.

According to some example embodiments, an electronic device includes theoptical filter, the image sensor or the camera.

Desired optical properties for light in near-infrared wavelength spectrawith a thin thickness may be effectively implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view showing an arrangement of a plurality of unitcells in a combination structure according to some example embodiments,

FIG. 2 is a schematic top plan view showing an enlarged example of theregion A of the combination structure 1 of FIG. 1,

FIG. 3 is a schematic cross-sectional view showing an enlarged exampleof the region A of the combination structure 1 of FIG. 1,

FIG. 4 is a schematic cross-sectional view showing another enlargedexample of the region A of the combination structure 1 of FIG. 1,

FIG. 5 is a schematic cross-sectional view showing another enlargedexample of the region A of the combination structure 1 of FIG. 1,

FIG. 6 is a schematic cross-sectional view showing another enlargedexample of the region A of the combination structure 1 of FIG. 1,

FIG. 7 is a schematic view illustrating an example of a camera moduleaccording to some example embodiments,

FIG. 8 is a schematic view illustrating an example of a camera moduleaccording to some example embodiments,

FIG. 9 is a cross-sectional view illustrating an example of an imagesensor according to some example embodiments,

FIG. 10 is a cross-sectional view illustrating another example of animage sensor according to some example embodiments,

FIG. 11 is a cross-sectional view illustrating another example of animage sensor according to some example embodiments,

FIG. 12 is a cross-sectional view illustrating another example of animage sensor according to some example embodiments,

FIG. 13 is a graph showing an optical spectrum of a nanostructure arrayaccording to an example,

FIG. 14 is a graph showing a transmission spectrum of a combinationstructure according to an example,

FIG. 15 is a graph showing transmission spectra according to Examples 1to 4 and Reference Examples 1 and 2,

FIG. 16 is a graph showing reflection spectra according to Example 1 to4 and Reference Examples 1 and 2,

FIG. 17 is a graph showing absorption spectra according to Examples 1 to4 and Reference Examples 1 and 2,

FIG. 18 is a graph showing transmission spectra according to Examples 1,5, and 6 and Reference Example 3,

FIG. 19 is a graph showing reflection spectra according to Examples 1,5, and 6 and Reference Example 3, and

FIG. 20 is a graph showing absorption spectra according to Examples 1, 5and 6 and Reference Example 3.

DETAILED DESCRIPTION

Hereinafter, example embodiments will be described in detail so that aperson skilled in the art would understand the same. This disclosuremay, however, be embodied in many different forms and is not construedas limited to the example embodiments set forth herein.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “on” another element, it can be directly on the other element orintervening elements may also be present. In contrast, when an elementis referred to as being “directly on” another element, there are nointervening elements present.

Hereinafter, a combination structure according to some exampleembodiments is described with reference to drawings.

FIG. 1 is a top plan view showing an arrangement of a plurality of unitcells in a combination structure according to some example embodiments,FIG. 2 is a schematic top plan view showing an enlarged example of theregion A of the combination structure 1 of FIG. 1, and FIG. 3 is aschematic cross-sectional view showing an enlarged example of the regionA of the combination structure 1 of FIG. 1.

A combination structure 10 according to some example embodimentsincludes a plurality of unit cells (U) arranged repeatedly along anin-plane direction, for example a plurality of unit cells (U) areregularly or periodically along rows and/or columns. For example, thecombination structure 10 may include a plurality of unit cells arrangedrepeatedly or periodically (e.g., in a pattern) in a plane to establishan in-plane (e.g., two-dimensional) pattern (e.g., “array”) of unitcells (U). A plurality of unit cells (U) arranged repeatedly in one ormore in-plane directions may be referred to herein interchangeably as anin-plane pattern of unit cells (U), where said in-plane pattern mayinclude at least one row pattern and/or column pattern of unit cells (U)and/or an array of unit cells (U) arranged in at least one row and/or atleast one column (e.g., a plurality of rows and a plurality of columns).

Each unit cell (U) includes one or more three-dimensional nanostructures11 a and a light-absorbing layer 12. In some example embodiments, agiven unit cell (U) may include a single nanostructure 11 a and thelight-absorbing layer 12, and it will be understood that descriptionspresented herein with regard to “the nanostructures 11 a” and/or aplurality of nanostructure 11 a may apply to nanostructures 11 a in aplurality of unit cells (U) where each unit cell (U) includes a single,individual nanostructure 11 a instead of a plurality of nanostructures11 a.

In some example embodiments, each unit cell (U) may include two or morenanostructures 11 a. In the drawing, in some example embodiments, thestructure in which two nanostructures 11 a are included in each unitcell (U) is illustrated but some example embodiments are not limitedthereto. Each unit cell (U) may include two or more nanostructures 11 a,for example 2 to 10, 2 to 8, 2 to 7, 2 to 6, or 2 to 5 nanostructures 11a.

In some example embodiments, a unit cell (U) includes a plurality ofnanostructures 11 a that may be arranged repeatedly or periodicallyalong a row and/or column in a plurality of unit cells (U) to form ananostructure array 11. Restated, the plurality of nanostructures 11 amay define a nanostructure array 11 in the plurality of unit cells (U).The nanostructure array 11 may be a structure having optical propertiescalled metamaterials or metastructures, and may exhibit unique opticalproperties that do not appear in two-dimensional planar structures,according to a repetitive or periodic arrangement of a plurality ofthree-dimensional nanostructures 11 a.

The nanostructures 11 a may include a high refractive index materialhaving a high refractive index. The refractive index may have awavelength distribution and the nanostructures 11 a may each include ahigh refractive index material having a refractive index at about 900 nmto about 1000 nm (e.g., about 940 nm) of for example greater than orequal to about 2.0, greater than or equal to about 2.3, greater than orequal to about 2.5, greater than or equal to about 3.0, greater than orequal to about 3.5, or greater than or equal to about 4.0. In someexample embodiments, a refractive index of the nanostructures 11 a maybe about 2.0 to about 5.0, about 2.3 to about 5.0, about 2.5 to about5.0, about 2.0 to about 4.0, about 2.3 to about 4.0, about 2.5 to about4.0, or about 2.5 to about 3.5. In some example embodiments, thenanostructures 11 a may each include an insulator, a conductor, asemiconductor, or a combination thereof having the refractive index, forexample an oxide, a nitride, a sulfide, a metal, a semiconductor, asemiconductor compound, or a combination thereof, for example a titaniumoxide, a zinc oxide, an indium oxide, a zirconium oxide, silicon,aluminum, a Group III-V semiconductor compound, or a combinationthereof, but are not limited thereto.

When the terms “about” or “substantially” are used in this specificationin connection with a numerical value, it is intended that the associatednumerical value include a tolerance of ±10% around the stated numericalvalue. When ranges are specified, the range includes all valuestherebetween such as increments of 0.1%.

The one or more nanostructures 11 a may each be a three dimensionalstructure having a particular (or, alternatively, predetermined) width(W) and thickness (t), in some example embodiments, a rectangularparallelepiped shape, a right hexahedral shape, a cylindrical shape, ora disk shape, but are not limited thereto. A cross-sectional shape ofthe nanostructures 11 a may be for example a rectangle or a square.

The plurality of nanostructures 11 a may be arranged with a particular(or, alternatively, predetermined) period (p) and/or gap (g), whereinthe period (p) may be a length between centers of the adjacentnanostructures 11 a, and the gap (g) may be a length between facingsurfaces of the adjacent nanostructures 11 a.

The nanostructure array 11 and/or the nanostructures 11 a may beconfigured to reflect or absorb light of a particular (or,alternatively, predetermined) wavelength and thus exhibit opticalproperties, in some example embodiments, reflect or absorb light of adesired wavelength by controlling a shape, geometry, dimension, and/ororientation of the nanostructures 11 a and/or an arrangement of thenanostructure array 11. In some example embodiments, one or moredimensions of the nanostructures 11 a may be a subwavelength which issmaller than a wavelength of light for reflection or absorption (e.g.,smaller than the particular wavelength). Herein, the one or moredimensions of the nanostructures 11 a may include a width and/or athickness, when the nanostructures 11 a has the cylindrical or diskshape, the width of the nanostructures 11 a may be a diameter.

The nanostructure array 11 may be configured to reflect or absorb lightof a particular (or, alternatively, predetermined) wavelength belongingto a near-infrared wavelength spectrum (e.g., a particular near-infraredwavelength spectrum), wherein one or more dimensions of thenanostructures 11 a (e.g., one or more of width (W), diameter, thickness(t), period (p), gap (g), any combination thereof, or the like) may beless than the particular (or, alternatively, predetermined)near-infrared wavelength belonging to the near-infrared wavelengthspectrum. It will be understood that the “near-infrared wavelengthspectrum” as described herein with regard to the nanostructures 11 aand/or the light-absorbing layer 12 may refer to the same near-infraredwavelength spectrum. Herein, the near-infrared wavelength spectrum maybe greater than about 700 nm and less than or equal to about 1200 nm,within the range, for example greater than about 700 nm and less than orequal to about 1100 nm, about greater than about 700 nm and less than orequal to about 1000 nm, about 750 nm to about 1100 nm, about 750 nm toabout 1000 nm, about 800 nm to about 1000 nm, about 850 nm to about 990nm, about 870 nm to about 990 nm, or about 890 nm to about 990 nm. Forexample, the one or more dimensions of the nanostructures 11 a (e.g.,one or more of width (W), diameter, thickness (t), period (p), gap (g),any combination thereof, or the like) may be less than the particular(or, alternatively, predetermined) near-infrared wavelength, where theparticular near-infrared wavelength is in a range of, for example,greater than about 700 nm and less than or equal to about 1200 nm,within the range, for example greater than about 700 nm and less than orequal to about 1100 nm, about greater than about 700 nm and less than orequal to about 1000 nm, about 750 nm to about 1100 nm, about 750 nm toabout 1000 nm, about 800 nm to about 1000 nm, about 850 nm to about 990nm, about 870 nm to about 990 nm, or about 890 nm to about 990 nm.

The width (W) of the nanostructures 11 a may be for example less than orequal to about 1100 nm, within the range for example about 100 nm toabout 1000 nm, about 100 nm to about 800 nm, about 100 nm to about 500nm, about 200 nm to about 500 nm, or about 300 nm to about 500 nm.

The thickness (t) of the nanostructures 11 a may be for example lessthan or equal to about 1100 nm, within the range for example about 50 nmto about 1000 nm, about 50 nm to about 800 nm, about 50 nm to about 700nm, about 50 nm to about 600 nm, about 50 nm to about 500 nm, about 100nm to about 500 nm, about 150 nm to about 500 nm, or about 200 nm toabout 400 nm.

The gap (g) of the nanostructures 11 a may be for example less than orequal to about 1100 nm, within the range for example about 50 nm toabout 1000 nm, about 50 nm to about 500 nm, about 50 nm to about 400 nm,about 70 nm to about 400 nm, about 70 nm to about 300 nm, or about 80 nmto about 300 nm.

The period (p) of the nanostructures 11 a may be for example less thanor equal to about 1100 nm, within the range for example about 200 nm toabout 1000 nm, about 200 nm to about 800 nm, about 200 nm to about 700nm, about 300 nm to about 700 nm, or about 400 nm to about 700 nm.

The nanostructure array 11 includes a plurality of nanostructures 11 awhich are arranged repeatedly or periodically along a row and/or columnin a plurality of unit cells (U) as described above, and a portion ofthe plurality of nanostructures 11 a may differ at least one of adimension such as a width (w), a thickness (t), a gap (g), and/or aperiod (p), compared with the rest of the nanostructures 11 a.

In some example embodiments, at least one nanostructure 11 a out of theplurality of nanostructures 11 a in each unit cell (U) may have adifferent dimension from those of the rest (e.g., a remainder portion)of the nanostructures 11 a. In some example embodiments, when each unitcell (U) includes a first nanostructure 11 a-1 and a secondnanostructure 11 a-2, a dimension of the first nanostructure 11 a-1 maydiffer from the corresponding dimension of the second nanostructure 11a-2.

In some example embodiments, a width (W1) of the first nanostructure 11a-1 may be different from a width (W₂) of the second nanostructure 11a-2. In some example embodiments, the width (W1) of the firstnanostructure 11 a-1 may be larger than the width (W2) of the secondnanostructure 11 a-2, in some example embodiments, about 1.05 times toabout 10 times as large as the width (W2) of the second nanostructure 11a-2, and within the range, about 1.05 times to about 5 times, about 1.1times to about 5 times, about 1.2 times to about 5 times, about 1.5times to about 5 times or about twice to about 5 times as large as thewidth (W2) of the second nanostructure 11 a-2.

In some example embodiments, a thickness (t1) of the first nanostructure11 a-1 may differ from a thickness (t2) of the second nanostructure 11a-2. In some example embodiments, the thickness (t1) of the firstnanostructure 11 a-1 may be thicker than the thickness (t2) of thesecond nanostructure 11 a-2, in some example embodiments, about 1.05times to about 10 times as large as the thickness (t2) of the secondnanostructure 11 a-2 and within the range, about 1.05 times to about 5times, about 1.1 times to about 5 times, about 1.2 times to about 5times, about 1.5 times to about 5 times, or about twice to about 5 timesthe thickness (t2) of the second nanostructure 11 a-2.

In some example embodiments, a gap (g) between two nanostructures 11 ain each unit cell (U) or its adjacent unit cell (U) may be differentfrom a gap (g) between the rest of the nanostructures 11 a. In someexample embodiments, for example, as shown in at least FIG. 3, where thenanostructure array 11 includes nanostructures 11 a-1 to 11 a-4 arrangedin parallel (e.g., a parallel pattern of the nanostructures 11 a-1 to 11a-4) when the first nanostructure 11 a-1 and the second nanostructure 11a-2 are included in a first unit cell (U1), a third nanostructure 11 a-3and a fourth nanostructure 11 a-4 are included in a second unit cell(U2), the gap (g1) between the first nanostructure 11 a-1 and the secondnanostructure 11 a-2 may be different from a gap (g2) between the secondnanostructure 11 a-2 and the third nanostructure 11 a-3.

As described herein, where any dimension is described to be differentfrom any other dimension (e.g., gap (g1) being different from gap (g2)as described above), it will be understood that the magnitude of thedimension may be different from the magnitude of the other dimension(e.g., the magnitude of gap (g1) may be different from the magnitude ofgap (g2)).

As shown in FIG. 3, the first unit cell U1 may include first and secondnanostructures 11 a-1 and 11 a-2, a second unit cell U2 that is adjacentto unit cell U1 may include third and fourth nanostructures 11 a-3 and11 a-4, the first through fourth nanostructures 11 a-1 to 11 a-4 maydefine a linear sequence of nanostructures 11 a extending in onedirection, and a magnitude of a gap (g1) between the first and secondnanostructures 11 a-1 and 11 a-2 may be different from a magnitude of agap (g2) between the second and third nanostructures 11 a-2 and 11 a-3.

In some example embodiments, the gap (g1) between the firstnanostructure 11 a-1 and the second nanostructure 11 a-2 may be smallerthan the gap (g2) between the second nanostructure 11 a-2 and the thirdnanostructure 11 a-3, in some example embodiments, about 0.2 times toabout 0.9 times as large as the gap (g2) between the secondnanostructure 11 a-2 and the third nanostructure 11 a-3.

In some example embodiments, the gap (g1) between the firstnanostructure 11 a-1 and the second nanostructure 11 a-2 may be largerthan the gap (g2) between the second nanostructure 11 a-2 and the thirdnanostructure 11 a-3, in some example embodiments, about 1.05 times toabout 5 times as large as the gap (g2) between the second nanostructure11 a-2 and the third nanostructure 11 a-3.

However, it is not limited thereto, and when at least threenanostructures 11 a are included in one unit cell (U), gaps (g) betweentwo neighboring nanostructures 11 a in one unit cell may differ oneanother, in some example embodiments, one gap (g) between twoneighboring nanostructures 11 a may be about 0.2 times to about 0.9times or about 1.05 times to about 5 times as large as another gap (g)of another two neighboring nanostructures 11 a.

In some example embodiments, a period (p) between two nanostructures 11a in each unit cell (U) or its neighboring unit cell (U) may differ fromanother period (p) between the rest of the nanostructures 11 a. In someexample embodiments, when the first nanostructure 11 a-1 and the secondnanostructure 11 a-2 are included in a first unit cell (U1), and thethird nanostructure 11 a-3 and the fourth nanostructure 11 a-4 areincluded in a second unit cell (U2), the period (p1) between the firstnanostructure 11 a-1 and the second nanostructure 11 a-2 may differ fromthe period (p2) between the second nanostructure 11 a-2 and the thirdnanostructure 11 a-3.

In some example embodiments, a dimension, for example a width (W) and/ora thickness (t) of at least one nanostructure 11 a out of the pluralityof nanostructures 11 a in each unit cell (U) may differ from adimension, for example a width (W) and/or a thickness (t)), of the othernanostructures 11 a, and the gap (g) and/or the period (p) between theplurality of nanostructures 11 a in each unit cell (U) or itsneighboring unit cell (U) may differ from gaps (g) and/or periods (p)between the other nanostructures 11 a. In some example embodiments, whenthe first nanostructure 11 a-1 and the second nanostructure 11 a-2 areincluded in the first unit cell (U1), and the third nanostructure 11 a-3and the fourth nanostructure 11 a-4 are included in the second unit cell(U2), the width (W1) and/or the thickness (t1) of the firstnanostructure 11 a-1 may differ from the width (W2) and/or the thickness(t2) of a second nanostructure 11 a-2, and the gap (g1) between thefirst nanostructure 11 a-1 and the second nanostructure 11 a-2 maydiffer from the gap (g2) between the second nanostructure 11 a-2 and thethird nanostructure 11 a-3.

In this way, a portion of the nanostructures 11 a comprising thenanostructure array 11 may be changed with respect to a dimension and/oran alignment to modify an optical spectrum of the nanostructure array 11having a consistent dimension and alignment of the nanostructures 11 a.

In some example embodiments, a transmission spectrum and a reflectionspectrum of the nanostructure array 11 having consistent dimension andalignment of the nanostructures 11 a have a single peak in anear-infrared wavelength spectrum, but a transmission spectrum and areflection spectrum of the nanostructure array 11 having differentdimension and/or alignment of a portion of the nanostructures 11 a mayhave two or more separate peaks in the near-infrared wavelengthspectrum. Herein, the near-infrared wavelength spectrum may be greaterthan about 700 nm and less than or equal to about 1200 nm, within therange, for example greater than about 700 nm and less than or equal toabout 1100 nm, about 700 nm to about 1000 nm, about 750 nm to about 1100nm, about 750 nm to about 1000 nm, about 800 nm to about 1000 nm, about850 nm to about 990 nm, about 870 nm to about 990 nm, or about 890 nm toabout 990 nm.

In this way, the transmission spectrum and the reflection spectrum ofthe nanostructure array 11 have two or more separate peaks in theparticular (or, alternatively, predetermined) near-infrared wavelengthspectrum and thus may widen a wavelength width exhibiting particular(or, alternatively, predetermined) transmittance and reflectancecompared with the spectra having a single peak.

FIG. 13 is a graph showing an optical spectrum of a nanostructure arrayaccording to an example.

Referring to FIG. 13, a transmission spectrum (T₁) of the nanostructurearray 11 has two separate peaks in a near-infrared wavelength spectrum,in some example embodiments, two separate local minimum points (relativeminimum points, M₁ and M₂) and a local maximum point (M₃) between thetwo separate local minimum points (M₁ and M₂). Restated, thetransmission spectrum (T₁) of the nanostructure array 11 may have afirst local minimum point (M₁) and a second local minimum point (M₂)separated from each other, and a first local maximum point (M₃) betweenthe first local minimum point (M₁) and the second local minimum point(M₂). Herein, the local minimum points (M₁ and M₂) may be an inflectionpoint having lower transmittance than neighboring wavelengths, and thelocal maximum point (M₃) may be an inflection point having highertransmittance than the neighboring wavelengths. A minimum transmittanceof the nanostructure array 11 may be transmittance at one of the localminimum points (M₁ or M₂).

Herein, the transmittance at the local minimum points (M₁ and M₂) andtransmittance at the local maximum point (M₃) may have a relativelylarge difference. In some example embodiments, the difference betweenthe transmittance at one of the local minimum points (e.g., either M₁ orM₂) and the transmittance of the local maximum point (M₃) may be larger(‘greater”) than about 30%, greater than about 30% and less than orequal to about 80%, about 40% to about 80%, about 40% to about 70%, orabout 40% to about 60%. In some example embodiments, the transmittanceat the local minimum points (M₁ and M₂) may be less than or equal toabout 10%, less than or equal to about 5%, less than or equal to about3%, less than or equal to about 2%, less than or equal to about 1%, lessthan or equal to about 0.5%, or about 0%, and the transmittance at thelocal maximum point (M₃) may be greater than about 10%, greater thanabout 10% and less than or equal to about 80%, about 15% to about 80%,about 20% to about 80%, about 25% to about 80%, about 30% to about 70%,about 35% to about 70%, about 40% to about 70%, or about 45% to about70%.

In some example embodiments, when absorptance of the nanostructure array11 in a near-infrared wavelength spectrum is substantially 0, areflection spectrum R₁ of the nanostructure array 11 in thenear-infrared wavelength spectrum may be symmetrical to a transmissionspectrum (T₁), and the reflection spectrum R₁ has two separate localmaximum points (M₄ and M₅) and a local minimum point (M₆) between thetwo separate local maximum points (M₄ and M₅).

The nanostructure array 11 according to some example embodiments mayhave a modified optical spectrum and widen a wavelength showingparticular (or, alternatively, predetermined) transmittance comparedwith a nanostructure array 11 having consistent dimension and alignmentof the nanostructures 11 a. This modified optical spectrum of thenanostructure array 11 is complementarily combined with thelight-absorbing layer 12 disposed adjacently thereto and thus mayexhibit high light absorption characteristics in a wide wavelengthwidth.

The light-absorbing layer 12 may be configured to absorb light of aparticular (or, alternatively, predetermined) wavelength. As shown in atleast FIG. 3, the light-absorbing layer 12 may be disposed adjacent tothe nanostructure array 11 and for example may be in contact with someor all of the nanostructures 11 a of the nanostructure array 11. Asshown in at least FIG. 3, the light-absorbing layer 12 may be under(e.g., beneath) the plurality of the nanostructures 11 a and may be incontact with a lower surface of some or all of the plurality ofnanostructures 11 a. In the drawing shown in at least FIG. 3, as anexample, the light-absorbing layer 12 is disposed under thenanostructures 11 a, but the present disclosure is not limited thereto.The light-absorbing layer 12 may be disposed at at least one of a lowersurface, an upper surface, and/or one or more side surfaces of one ormore of the nanostructures 11 a and may be in contact with at least oneof a lower surface, an upper surface, and/or one or more side surfacesof one or more of the nanostructures 11 a.

The light-absorbing layer 12 includes a light-absorbing materialconfigured to absorb light of a particular (or, alternatively,predetermined) wavelength. The light-absorbing material may be one ormore of an organic material, an inorganic material, organic/inorganicmaterial, or a combination thereof.

In some example embodiments, the light-absorbing layer 12 may include anear-infrared absorbing material configured to absorb light in at leasta portion of near-infrared wavelength spectra. As described herein,“wavelength spectra” may include one or more wavelength spectra and mayinclude a single wavelength spectrum, and in some example embodimentsthe light-absorbing layer 12 may include a near-infrared absorbingmaterial configured to absorb light in at least a portion of thenear-infrared wavelength spectrum, which may be the same near-infraredwavelength spectrum that includes a near-infrared wavelength that islarger than one or more dimensions of the unit cells. For example, thenear-infrared absorbing material may be configured to absorb light in atleast a portion of a wavelength spectrum of greater than about 700 nmand less than or equal to about 1200 nm and a maximum absorptionwavelength (λ_(max,A)) of the near-infrared absorbing material may forexample belong to a range of greater than about 700 nm and less than orequal to about 1100 nm, greater than about 700 nm and less than or equalto about 1000 nm, about 750 nm to about 1100 nm, about 750 nm to about1000 nm, about 800 nm to about 1000 nm, about 850 nm to about 990 nm,about 870 nm to about 990 nm, or about 890 nm to about 990 nm.

The near-infrared absorbing material may be one or more materials, andis not particularly limited as long as it is configured to selectivelyabsorb light in a near-infrared wavelength spectrum. The near-infraredabsorbing material may be an organic material, an inorganic material, anorganic/inorganic material, and/or a combination thereof.

The near-infrared absorbing material may include for example a quantumdot, a quinoid metal complex compound, a polymethine compound, a cyaninecompound, a phthalocyanine compound, a merocyanine compound, anaphthalocyanine compound, an immonium compound, a diimmonium compound,a triarylmethane compound, a dipyrromethene compound, an anthraquinonecompound, a diquinone compound, a naphthoquinone compound, a squaryliumcompound, a rylene compound, a perylene compound, a pyrylium compound, asquaraine compound, a thiopyrylium compound, a diketopyrrolopyrrole)compound, a boron-dipyrromethene compound, a nickel-dithiol complexcompound, a croconium compound, a derivative thereof, or a combinationthereof, but is not limited thereto.

In some example embodiments, the light-absorbing layer 12 including thenear-infrared absorbing material may have a refractive index (n) in anear-infrared wavelength spectrum in a range of less than about 2.0,less than or equal to about 1.9, or less than or equal to about 1.8, forexample greater than or equal to about 1.1 and less than about 2.0,about 1.1 to about 1.9, or about 1.1 to about 1.8. In some exampleembodiments, an average refractive index (n) at a wavelength spectrum ofabout 900 nm to about 1000 nm (e.g., 940 nm) may be less than about 2.0,less than or equal to about 1.9, or less than or equal to about 1.8, forexample greater than or equal to about 1.1 and less than about 2.0,about 1.1 to about 1.9, or about 1.1 to about 1.8. In some exampleembodiments, the light-absorbing layer 12 including the near-infraredabsorbing material may have an extinction coefficient (k) in thenear-infrared wavelength spectrum of about 0.001 to about 0.5, forexample an extinction coefficient (k) in a wavelength spectrum of about900 nm to about 1000 nm (e.g., 940 nm) of about 0.01 to about 0.5.

The light-absorbing layer 12 may be formed from a composition includingthe aforementioned near-infrared absorbing material, in some exampleembodiments, a curing product of the composition.

The composition may optionally further include a binder, in addition tothe aforementioned near-infrared absorbing material. The binder may befor example an organic binder, an inorganic binder, an organic/inorganicbinder, or a combination thereof, and is not particularly limited aslong as it is a material capable of mixing with the near-infraredabsorbing material, dispersing in the near-infrared absorbing material,or binding the near-infrared absorbing materials. The binder may be acurable binder, for example a thermally curable binder, a photo-curablebinder, or a combination thereof.

The binder may be for example a (meth)acrylic binder, methyl cellulose,ethyl cellulose, hydroxypropyl methyl cellulose (HPMC), hydroxylpropylcellulose (HPC), xanthan gum, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), a cyclic olefin polymer (COP), carboxy methylcellulose, hydroxyl ethyl cellulose, silicone, an organic-inorganichybrid material, a copolymer thereof, or a combination thereof, but isnot limited thereto.

The near-infrared absorbing material may be for example included in anamount of about 0.01 to about 50 parts by weight, about 0.01 to about 30parts by weight, about 0.01 to about 20 parts by weight, about 0.01 toabout 15 parts by weight, or about 0.01 to about 10 parts by weightbased on 100 parts by weight of the binder.

The composition may optionally further include a solvent, in addition tothe aforementioned near-infrared absorbing material, and binder.

The composition may be coated on the base layer 13 that will bedescribed later, dried, and then optionally cured. The coating may befor example a spin coating, a slit coating, a bar coating, a bladecoating, a slot die coating, and/or an inkjet coating. The drying may befor example performed by natural drying, hot air drying, and/or a heattreatment at a higher temperature than the boiling point of theaforementioned solvent. The curing may be thermal curing, photo curing,or a combination thereof.

The light-absorbing layer 12 may have a thickness 12 t ranging fromabout 1 nm to about 1000 nm, within, the range, for example about 1 nmto about 800 nm, about 10 nm to about 700 nm, about 10 nm to about 500nm, or about 10 nm to about 300 nm.

The base layer 13 is disposed under the nanostructure array 11 and thelight-absorbing layer 12 and may support the nanostructure array 11 andthe light-absorbing layer 12. The base layer 13 may be a transparentbase layer and, in some example embodiments, have transmittance ofgreater than or equal to about 85% or greater than or equal to about 90%in a wavelength spectrum of about 400 nm to about 1000 nm.

The base layer 13 may have a lower refractive index than that of thenanostructures 11 a, in some example embodiments, an average refractiveindex of less than or equal to about 1.7 in a range of about 900 nm toabout 1000 nm (e.g., about 940 nm), in some example embodiments, in arange of about 1.4 to about 1.7. The base layer 13 may, in some exampleembodiments, include an organic material, an inorganic material, anorganic/inorganic material, or a combination thereof, in some exampleembodiments, oxide, nitride, sulfide, fluoride, a polymer, or acombination thereof, in some example embodiments, glass, silicon oxide,aluminum oxide, magnesium fluoride, polystyrene, polymethylmethacrylate,polycarbonate, or a combination thereof, but is not limited thereto. Thebase layer 13 may be omitted as needed.

The combination structure 10 may have a thickness 10 t of less than orequal to about 10 μm, less than or equal to about 5 μm, less than orequal to about 3 μm, less than or equal to about 2 μm, less than orequal to about 1 μm, less than or equal to about 900 nm, less than orequal to about 800 nm, less than or equal to about 700 nm, less than orequal to about 600 nm, or less than or equal to about 500 nm. In someexample embodiments, the thickness of the combination structure 10 maybe in a range of about 100 nm to about 10 μm, about 100 nm to about 5μm, about 100 nm to about 3 μm, about 100 nm to about 2 μm, about 100 nmto about 1 μm, about 100 nm to about 900 nm, about 100 nm to about 800nm, about 100 nm to about 700 nm, about 100 nm to about 600 nm, or about100 nm to about 500 nm.

The combination structure 10 may exhibit high light absorptioncharacteristics at a thin thickness by combining the nanostructure array11 and the light-absorbing layer 12. This is based on unique opticalproperties of the nanostructure array 11 called to be a metamaterial ora metastructure, and the nanostructure array 11 and/or thenanostructures 11 a may confine incident light of a particular (or,alternatively, predetermined) wavelength, and the confined light by thenanostructure array 11 and/or the nanostructures 11 a may bemulti-absorbed in the adjacent light-absorbing layer 12 and thus exhibita high absorption effect.

An amount of the multi-absorbed light may be greatly higher than anamount of the absorbed light in a structure without nanostructure array11, in which incident light from a structure having no nanostructurearray 11, that is, a planar structure once passes the light-absorbinglayer 12.

In addition, as described above, a portion of the nanostructures 11 aforming the nanostructure array 11 may be changed to have differentdimensions and/or alignments to exhibit a transmission spectrum havingtwo separate peaks and thus a transmission spectrum having a relativelywide wavelength width.

The combination structure 10 may stably decrease transmittance andreflectance and increase absorptance in a relatively wide wavelengthwidth due to the complementary combination of the nanostructure array 11and the light-absorbing layer 12. The light-absorbing layer 12 may beconfigured to absorb light in a wavelength spectrum between two separatepeaks in the transmission spectrum of the above nanostructure array 11and thus decrease transmittance but increase absorptance in a widewavelength width in a near-infrared wavelength spectrum of thecombination structure 10. Ultimately, the combination structure 10 maydecrease transmittance but increase absorptance in a wide range of thenear-infrared wavelength spectrum and thus effectively block light inthe near-infrared wavelength spectrum.

FIG. 14 is a graph showing a transmission spectrum of a combinationstructure according to an example.

Referring to FIG. 14, the transmission spectrum (T₂) of the combinationstructure 10 is overlapped with at least a portion of the transmissionspectrum (T₁) of the nanostructure array 11, but a wavelength width (W₂)of the transmission spectrum (T₂) of the combination structure 10 may bewider than a wavelength width (W₁) of the transmission spectrum (T₁) ofthe nanostructure array 11.

In some example embodiments, a wavelength width (W₂) at 50%transmittance in a near-infrared wavelength spectrum (e.g., the sameparticular near-infrared wavelength spectrum that the near-infraredabsorbing material of the light-absorbing layer 12 is configured toabsorb light in at least a portion thereof) of the transmission spectrum(T₂) of the combination structure 10 may be wider than a wavelengthwidth (W₁) at 50% transmittance in the near-infrared wavelength spectrumof the transmission spectrum (T₁) of the nanostructure array 11, in someexample embodiments, about 1.2 times to about 10 times and within therange, about 1.2 times to about 5 times or about 1.2 times to about 3times as large as the wavelength width (W₁) at 50% transmittance in thenear-infrared wavelength spectrum of the transmission spectrum (T₁) ofthe nanostructure array 11.

In some example embodiments, the wavelength width (W₂) at thetransmittance of 50% in the near-infrared wavelength spectrum of thetransmission spectrum (T₂) of the combination structure 10 may be about38 nm to about 200 nm and within the range, about 40 nm to about 200 nm,about 40 nm to about 180 nm, or about 43 nm to about 150 nm.

In some example embodiments, the transmission spectrum (T₂) of thecombination structure 10 in the near-infrared wavelength spectrum alsomay have two separate peaks, in some example embodiments, two separatelocal minimum points (Q₁ and Q₂) and a local maximum point (Q₃) betweenthe two separate local minimum points (Q₁ and Q₂) like the transmissionspectrum (T₁) of the nanostructure array 11 in the near-infraredwavelength spectrum. Restated, the transmission spectrum (T₁) of thecombination structure 10 may have a first local minimum point (a) and asecond local minimum point (Q₂) separated from each other, and a firstlocal maximum point (Q₃) between the first local minimum point (a) andthe second local minimum point (Q₂) Herein, the local minimum points (Q₁and Q₂) may be inflection points having lower transmittance thanneighboring wavelength spectra, and the local maximum point (Q₃) may bean inflection point having higher transmittance than the neighboringwavelength spectra. Minimum transmittance of the combination structure10 may be transmittance at one of the local minimum points (Q₁ or Q₂).

As described above, the light-absorbing layer 12 may be configured toabsorb light in a wavelength spectrum between two separate peaks in thetransmission spectrum of the above nanostructure array 11, andaccordingly, a transmittance difference between at one of the localminimum points (e.g., at either Q₁ or Q₂) of the combination structure10 and at the local maximum point (Q₃) may be smaller than atransmittance difference between at one of the local minimum points (M₁or M₂) of the nanostructure array 11 and at the local maximum point(M₃). In some example embodiments, the transmittance difference betweenat one of the local minimum points (Q₁ or Q₂) of the combinationstructure 10 and at the local maximum point (Q₃) may be less than orequal to about 30%, about 0 to about 30%, about 0.1% to about 30%, about3% to about 30%, about 5% to about 30%, about 5% to about 20%, or about5% to about 10%. When the transmittance difference between at one of thelocal minimum points (Q₁ or Q₂) of the combination structure 10 and atthe local maximum point (Q₃) is about 0.5%, less than or equal to about0.3%, less than or equal to about 0.1% or 0, the transmission spectrummay substantially have a single peak.

In some example embodiments, an optical spectrum of the combinationstructure 10 may have a minimum transmission wavelength (λ_(min,T)) in awavelength spectrum of greater than about 700 nm and less than or equalto about 1200 nm, within the range, for example minimum transmissionwavelength (λ_(min,T)) of greater than about 700 nm and less than orequal to about 1100 nm, greater than about 700 nm and less than or equalto about 1000 nm, about 750 nm to about 1100 nm, about 750 nm to about1000 nm, about 800 nm to about 1000 nm, about 850 nm to about 990 nm,about 870 nm to about 990 nm, or about 890 nm to about 990 nm. Atransmittance of the combination structure 10 at the minimumtransmission wavelength (λ_(min,T)) may be less than or equal to about35%, within the range, in some example embodiments, less than or equalto about 32%, less than or equal to about 30%, less than or equal toabout 28%, less than or equal to about 25%, less than or equal to about22%, less than or equal to about 20%, less than or equal to about 18%,less than or equal to about 15%, less than or equal to about 10%, orless than or equal to about 5%.

In some example embodiments, a reflectance in the near-infraredwavelength spectrum of the combination structure 10 may be significantlyreduced compared with the reflectance in the near-infrared wavelengthspectrum of the nanostructure array 11, and may be for example less thanor equal to about 25%, less than or equal to about 22%, less than orequal to about 20%, less than or equal to about 15%, less than or equalto about 10%, less than or equal to about 5%, less than or equal toabout 2%, or less than or equal to about 1%.

In some example embodiments, an absorptance of the combination structure10 may be 100% minus the transmittance and reflectance, which may be forexample expressed as the absorptance=100−transmittance−reflectance. Insome example embodiments, an absorption spectrum of the combinationstructure 10 may have a maximum absorption wavelength (λ_(max,A)) in awavelength spectrum of greater than about 700 nm and less than or equalto about 1200 nm, within the range for example greater than about 700 nmand less than or equal to about 1100 nm, greater than about 700 nm andless than or equal to about 1000 nm, about 750 nm to about 1100 nm,about 750 nm to about 1000 nm, about 800 nm to about 1000 nm, about 850nm to about 990 nm, about 870 nm to about 990 nm, or about 890 nm toabout 990 nm. An absorptance at a maximum absorption wavelength(λ_(max,A)) of the combination structure 10 may be greater than or equalto about 40%, greater than or equal to about 43%, greater than or equalto about 45%, or greater than or equal to about 50%, within the range,for example greater than or equal to about 55%, greater than or equal toabout 60%, greater than or equal to about 65%, or greater than or equalto about 70%.

FIG. 4 is a schematic cross-sectional view showing another enlargedexample of the region A of the combination structure 1 of FIG. 1.

According to some example embodiments, a combination structure 10includes the nanostructure array 11 including the plurality ofnanostructures 11 a; the light-absorbing layer 12; and the base layer13, like some example embodiments, including the example embodimentsshown in at least FIGS. 1-3.

However, in the combination structure 10 according to some exampleembodiments including the example embodiments shown in at least FIG. 4,unlike some example embodiments, including the example embodiments shownin FIGS. 1-3, the nanostructure array 11 and the light-absorbing layer12 are disposed in the same layer. In some example embodiments, thelight-absorbing layer 12 may be disposed at the side of a plurality ofnanostructures 11 a, the light-absorbing layer 12 may be in contact witha side of the nanostructure 11 a.

FIG. 5 is a schematic cross-sectional view showing another enlargedexample of the region A of the combination structure 1 of FIG. 1.

According to some example embodiments including the example embodimentsshown in at least FIG. 5, a combination structure 10 includes thenanostructure array 11 including the plurality of nanostructures 11 a;the light-absorbing layer 12; and the base layer 13, like some exampleembodiments including the example embodiments shown in at least FIG. 4.

However, the combination structure 10 according to some exampleembodiments including the example embodiments shown in at least FIG. 5,unlike some example embodiments including the example embodiments shownin at least FIG. 4, may include the light-absorbing layer 12 disposedunder the nanostructure array 11 and in the same layer as thenanostructure array 11. In some example embodiments, the light-absorbinglayer 12 may be disposed at the side of and under a plurality ofnanostructures 11 a, and the light-absorbing layer 12 may respectivelycontact at the side of and under the nanostructure 11 a.

FIG. 6 is a schematic cross-sectional view showing another enlargedexample of the region A of the combination structure 1 of FIG. 1.

According to some example embodiments including the example embodimentsshown in at least FIG. 4, a combination structure 10 includes thenanostructure array 11 including the plurality of nanostructures 11 a;the light-absorbing layer 12; and the base layer 13, like some exampleembodiments including the example embodiments shown in at least FIG. 3.

However, the combination structure 10 according to some exampleembodiments including the example embodiments shown in at least FIG. 6,unlike some example embodiments including the example embodiments shownin at least FIG. 4, may include the light-absorbing layer 12 on the topand at the side of nanostructure array 11. In some example embodiments,the light-absorbing layer 12 may respectively contact on and at the sideof the nanostructure 11 a.

The aforementioned combination structure 10 may exhibit high lightabsorption characteristics with a thin thickness by increasing lightabsorption in at least a portion of near-infrared wavelength spectra,thereby realizing a thin thickness optical filter. In some exampleembodiments, the combination structure 10 configured to selectivelyabsorb light in a near-infrared wavelength spectrum may be configured toeffectively transmit light in a visible wavelength spectrum andeffectively absorb light in a near-infrared wavelength spectrum and thusmay be effectively applied as an optical filter configured to blocklight in the near-infrared wavelength spectrum in a sensor sensing lightlike an image sensor. In addition, the combination structure 10 mayexhibit sufficient light absorption characteristics with a thinthickness and accordingly, may be integrated in the sensor like theimage sensor and thus realize an internal optical filter, as describedabove.

The combination structure 10 may be applied as an optical filter to allapplications for filtering light of a particular (or, alternatively,predetermined) wavelength spectrum, and may be effectively applied as anear-infrared cut filter configured to filter light in a near-infraredwavelength spectrum. The optical filter may be usefully applied to anelectronic device including for example an image sensor, a cameramodule, and the like. The electronic device may be a digital camera, acamcorder, a monitoring camera such as CCTV, an in-car camera, a medicalcamera, a cell phone having a built-in or external camera, a computerhaving a built-in or external camera, a laptop computer having abuilt-in or external camera, a robot device having a built-in orexternal camera and the like but is not limited thereto.

Hereinafter, an example of a camera module provided with theaforementioned combination structure 10 is described.

FIG. 7 is a schematic view showing an example of a camera moduleaccording to some example embodiments.

Referring to FIG. 7, a camera module 20, also referred to herein assimply a “camera,” includes a lens barrel 21, a housing 22, an opticalfilter 10A, and an image sensor 23. In some example embodiments, thelens barrel 21 and/or the housing 22 may be omitted.

The lens barrel 21 includes at least one lens imaging a subject, and thelens may be disposed along an optical axis direction. Herein, theoptical axis direction may be a vertical direction of the lens barrel21. The lens barrel 21 is internally housed in the housing 22 and unitedwith the housing 22. The lens barrel 21 may be moved in optical axisdirection inside the housing 22 for autofocusing.

The housing 22 supports and houses the lens barrel 21 and the housing 22may be open in the optical axis direction. Accordingly, incident lightfrom the housing 22 may reach the image sensor 23 through the lensbarrel 21 and the optical filter 10A.

The housing 22 may be equipped with an actuator for moving the lensbarrel 21 in the optical axis direction. The actuator may include avoice coil motor (VCM) including a magnet and a coil. However, variousmethods such as a mechanical driving system or a piezoelectric drivingsystem using a piezoelectric device except for the actuator may beadopted.

The optical filter 10A may include the aforementioned combinationstructure 10 and is the same as described above.

The optical filter 10A may have a thickness of less than or equal toabout 10 μm, less than or equal to about 5 μm, less than or equal toabout 3 μm, less than or equal to about 2 μm, less than or equal toabout 1 μm, less than or equal to about 900 nm, less than or equal toabout 800 nm, less than or equal to about 700 nm, less than or equal toabout 600 nm, or less than or equal to about 500 nm. In some exampleembodiments, the optical filter 10A may have a thickness of about 100 nmto about 10 μm, about 100 nm to about 5 μm, about 100 nm to about 3 μm,about 100 nm to about 2 μm, about 100 nm to about 1 μm, about 100 nm toabout 900 nm, about 100 nm to about 800 nm, about 100 nm to about 700nm, about 100 nm to about 600 nm, or about 100 nm to about 500 nm.

The image sensor 23 may concentrate an image of a subject and thus storeit as data, and the stored data may be displayed as an image through adisplay media.

The image sensor 23 may be mounted in a substrate (not shown) andelectrically connected to the substrate. The substrate may be, in someexample embodiments, a printed circuit board (PCB) or electricallyconnected to a printed circuit board, and the printed circuit may be, insome example embodiments, a flexible printed circuit (FPCB).

The image sensor 23 concentrates light passing the lens barrel 21 andthe optical filter 10A and generates a video signal and may be acomplementary metal-oxide semiconductor (CMOS) image sensor and/or acharge coupled device (CCD) image sensor.

FIG. 8 is a schematic view showing another example of a camera moduleaccording to some example embodiments.

Referring to FIG. 8, a camera module 20 according to some exampleembodiments includes the lens barrel 21, the housing 22, the opticalfilter 10A, and the image sensor 23, like some example embodiments,including the example embodiments illustrated in FIG. 7.

However, in the camera module 20 according to some example embodimentsincluding the example embodiments shown in at least FIG. 8, the opticalfilter 10A and the image sensor 23 may be in contact with each other,for example the optical filter 10A and the image sensor 23 may beintegrally provided to embody an optical filter-integrated image sensor23A, unlike some example embodiments including the example embodimentsshown in at least FIG. 7.

Hereinafter, an example of an optical filter-integrated image sensorwill be described with reference to a drawing. As an example of an imagesensor, a CMOS image sensor is described.

FIG. 9 is a cross-sectional view showing an example of an image sensoraccording to some example embodiments.

An integrated image sensor 23A according to some example embodimentsincludes an image sensor 23 including a semiconductor substrate 110, alower insulation layer 60, a color filter layer 70 and an upperinsulation layer 80; and an optical filter 10A.

The semiconductor substrate 110 may be a silicon substrate, and isintegrated with the photo-sensing devices 50 a, 50 b, and 50 c, andtransmission transistor (not shown). The photo-sensing devices 50 a, 50b, and 50 c may be photodiodes. In some example embodiments, thephoto-sensing device 50 a may be a blue photo-sensing device 50 aconfigured to sense light in a blue wavelength spectrum which passes ablue filter 70 a described later, the photo-sensing device 50 b may be agreen photo-sensing device 50 b configured to sense light in a greenwavelength spectrum which passes a green filter 70 b described later,and the photo-sensing device 50 c may be a red photo-sensing device 50 cconfigured to sense light in a red wavelength spectrum passes a redfilter 70 c described later. The photo-sensing devices 50 a, 50 b, and50 c and the transmission transistor may be integrated in each pixel.The photo-sensing devices 50 a, 50 b, and 50 c sense light and thesensed information may be transferred by the transmission transistor.

A metal wire (not shown) and a pad (not shown) are formed on thesemiconductor substrate 110. In order to decrease signal delay, themetal wire and pad may be made of a metal having low resistivity, insome example embodiments, aluminum (Al), copper (Cu), silver (Ag), andalloys thereof, but is not limited thereto. However, it is not limitedto the structure, and the metal wire and pad may be disposed under thephoto-sensing devices 50 a, 50 b, and 50 c.

The lower insulation layer 60 is formed on the metal wire and the pad.The lower insulation layer 60 may be made of an inorganic insulatingmaterial such as a silicon oxide and/or a silicon nitride, or a lowdielectric constant (low K) material such as SiC, SiCOH, SiCO, and SiOF.

A color filter layer 70 is formed on the lower insulation layer 60. Thecolor filter layer 70 includes a blue filter 70 a formed in a bluepixel, a green filter 70 b formed in a green pixel, and a red filter 70c formed in a red pixel. However, the present disclosure is not limitedthereto, but at least one of the blue filter 70 a, the green filter 70b, or the red filter 70 c may be replaced by a yellow filter, a cyanfilter, or a magenta filter.

The upper insulation layer 80 is formed on the color filter layer 70.The upper insulation layer 80 may provide a flat surface by reducingstepped portions formed by the color filter layer 70. The upperinsulation layer 80 may be made of an inorganic insulating material suchas silicon oxide and/or silicon nitride or an organic insulatingmaterial. The upper insulation layer 80 may be omitted as needed.

The optical filter 10A is formed on the upper insulation layer 80. Theoptical filter 10A may be the aforementioned combination structure 10.As described above, the optical filter 10A may include the nanostructurearray 11 including the plurality of nanostructures 11 a; thelight-absorbing layer 12; and the base layer 13, and may for exampleblock light in a wavelength spectrum except for a visible wavelengthspectrum such as a near-infrared wavelength spectrum. When theaforementioned upper insulation layer 80 is the same as the base layer13 of combination structure 10, any one of the upper insulation layer 80or the base layer 13 may be omitted. Detailed descriptions of thecombination structure 10 are the same as described above.

Focusing lens 85 may be further formed on the optical filter 10A.However, the present disclosure is not limited thereto, and the opticalfilter 10A may be disposed on the focusing lens 85. The focusing lens 85may control a direction of incident light and gather the light in oneregion. The focusing lens 85 may have a shape of, in some exampleembodiments, a cylinder or a hemisphere, but is not limited thereto.

A dual bandpass filter 90 may be disposed on the focusing lens 85. Thedual bandpass filter 90 may selectively transmit light in at least twowavelength spectra of incident light and may for example selectivelytransmit light in a visible wavelength spectrum and in a near-infraredwavelength spectrum. For example, the dual bandpass filter 90 may beconfigured to selectively transmit light of an entirety of the visiblewavelength spectrum and a portion (e.g., a limited portion) of thenear-infrared wavelength spectrum.

As described above, the optical filter 10A may effectively transmitlight in the visible wavelength spectrum and effectively absorb andblock light in the other regions like the near-infrared region exceptfor the visible wavelength spectrum and thus transfer pure light in thevisible wavelength spectrum to the image sensor and accordingly, reduceor prevent a crosstalk generated when a signal by light of the visiblewavelength spectrum is crossed and mingled with another signal by lightof a non-visible wavelength spectrum and particularly, the near-infraredwavelength spectrum. Restated, the optical filter 10A may be configuredto block light of at least a portion of a near-infrared wavelengthspectrum. For example, the optical filter 10A may be configured to blocksaid light of at least a portion of a near-infrared wavelength spectrum,of light that is incident on a surface of the optical filter 10A that isdistal from the semiconductor substrate 110, from passing through theoptical filter 10A to be incident on one or more portions and/orsurfaces of some or all of the image sensor 23.

Particularly, the optical filter 10A may have a thin thickness of lessthan or equal to about 10 μm, less than or equal to about 5 μm, lessthan or equal to about 3 μm, less than or equal to about 2 μm, or lessthan or equal to about 1 μm, and thus the optical filter 10A and theimage sensor 23 may be realized into an integrated image sensor 23A, andaccordingly, may realize thinness of an image sensor, a camera module,and an electronic device equipped therewith.

FIG. 10 is a cross-sectional view showing another example of an imagesensor according to some example embodiments.

According to some example embodiments including the example embodimentsshown in at least FIG. 10, an integrated image sensor 23A includes animage sensor 23 including the semiconductor substrate 110 integratedwith photo-sensing devices 50 a, 50 b, and 50 c, the lower insulationlayer 60, and the color filter layer 70; and the optical filter 10A,like some example embodiments including the example embodiments shown inat least FIG. 9.

However, according to some example embodiments, including the exampleembodiments illustrated in FIG. 10, in the integrated image sensor 23A,the optical filter 10A is disposed under the color filter layer 70,unlike the example embodiments illustrated in FIG. 9. Accordingly, asshown in FIGS. 9-10, in some example embodiments an image sensor 23A mayinclude a color filter layer 70, which may include one or more colorfilters 70 a, 70 b, or 70 c, which may be on (e.g., indirectly on) thesemiconductor substrate 110 and may be above (e.g., as shown in FIG. 10)or beneath (e.g., as shown in FIG. 9) the optical filter 10A. In thedrawing, the optical filter 10A is illustrated as an example with astructure in which the optical filter 10A is disposed between the lowerinsulation layer 60 and the color filter layer 70. However, the presentdisclosure is not limited thereto and the optical filter 10A may bedisposed between the semiconductor substrate 110 and the lowerinsulation layer 60.

FIG. 11 is a cross-sectional view showing another example of an imagesensor according to some example embodiments.

According to some example embodiments including the example embodimentsshown in at least FIG. 11, an integrated image sensor 23A includes animage sensor 23 including the semiconductor substrate 110 integratedwith photo-sensing device 50 a, 50 b, and 50 c, the lower insulationlayer 60, the color filter layer 70, and the upper insulation layer 80,and the optical filter 10A, like some example embodiments including theexample embodiments shown in at least FIG. 9.

However, according to some example embodiments including the exampleembodiments shown in at least FIG. 11, the integrated image sensor 23Amay include the photo-sensing device 50 d for sensing light belonging tothe infrared wavelength spectrum additionally integrated in thesemiconductor substrate 110 unlike some example embodiments includingthe example embodiments shown in at least FIG. 9. The color filter layer70 may include a transparent filter or a white color filter (not shown)at the position corresponding to the photo-sensing device 50 d or justhave an empty space without a separate filter.

The optical filter 10A may be disposed only either on or under the bluefilter 70 a, the green filter 70 b, and the red filter 70 c but neitheron nor under the transparent filter or the white color filter.

The dual bandpass filter may for example selectively transmit light in avisible wavelength spectrum and in a near-infrared wavelength spectrum.

In some example embodiments, the photo-sensing device 50 d may be usedas an auxiliary device to improve the sensitivity of the image sensor inlow-illumination environments.

In some example embodiments, the photo-sensing device 50 d may be usedas an infrared sensor configured to sense light in a near-infraredwavelength spectrum. The infrared sensor may extend a dynamic rangespecifically classifying a black/white contrast and thus increasesensing capability of a long distance 3-dimensional image. The infraredsensor may be for example a biometric sensor, for example an irissensor, a depth sensor, a fingerprint sensor, a blood vesseldistribution sensor, but is not limited thereto.

FIG. 12 is a cross-sectional view showing another example of an imagesensor according to some example embodiments.

According to some example embodiments including the example embodimentsshown in at least FIG. 12, an integrated image sensor 23A includes animage sensor 23 including the semiconductor substrate 110 integratedwith photo-sensing devices 50 a, 50 b, 50 c, and 50 d, the lowerinsulation layer 60, and the color filter layer 70; and the opticalfilter 10A, like some example embodiments including the exampleembodiments shown in at least FIG. 11.

However, according to some example embodiments including the exampleembodiments shown in at least FIG. 12, in the integrated image sensor23A, the optical filter 10A is disposed under the color filter layer 70,unlike some example embodiments including the example embodiments shownin at least FIG. 11. In the drawing, the optical filter 10A isillustrated as an example with a structure in which the optical filter10A is disposed between the lower insulation layer 60 and the colorfilter layer 70. However, the present disclosure is not limited theretoand the optical filter 10A may be disposed between the semiconductorsubstrate 110 and the lower insulation layer 60.

Hereinafter, some example embodiments are illustrated in more detailwith reference to examples. However, the present scope of the inventiveconcepts is not limited to these examples.

Manufacture of Near-infrared Absorbing Film Preparation Example 1

A near-infrared absorbing compound (Epolight™ 1178, Epolin) and acycloolefin polymer(poly[[octahydro-5-(methoxycarbonyl)-5-methyl-4,7-methano-1H-indene-1,3-diyl]-1,2-ethanediyl],CAS No. 123322-60-1, Sigma-Aldrich Co., Ltd.) are blended in a mixedsolvent of chloroform and cyclohexanone (a weight ratio of 1:1) toprepare a composition. Herein, the near-infrared absorbing compound andthe cycloolefin polymer in a weight ratio of 0.5:9.5 are used to have aconcentration of 6.5 wt % of the composition. Subsequently, thecomposition is spin-coated (3000 rpm, 20 seconds) on a SiO₂ substrate toform an about 800 nm-thick film.

Preparation Example 2

A film is formed according to the same method as Preparation Example 1except that the weight ratio of the near-infrared absorbing compound andthe cycloolefin polymer is changed into 1:9.

Preparation Example 3

A film is formed according to the same method as Preparation Example 1except that the weight ratio of the near-infrared absorbing compound andthe cycloolefin polymer is changed into 1.5:8.5.

Preparation Example 4

A film is formed according to the same method as Preparation Example 1except that the weight ratio of the near-infrared absorbing compound andthe cycloolefin polymer is changed into 2:8.

Comparative Preparation Example 1

A film is formed according to the same method as Preparation Example 1except that the near-infrared absorbing compound is not included.

Evaluation of Properties of Near-Infrared Absorbing Film

Properties of the films according to Preparation Examples 1 to 4 andComparative Preparation Example 1 are examined.

Transmittance and absorptance are measured by using a UV-VIS-NIRspectrophotometer (Solid Spec-3700 DUV, Shimadzu ScientificInstruments), and a film thickness is measured by using Alpha-Step(D-500 Stylus Profiler, KLA Corp.). The transmittance and absorptanceare used to obtain an extinction coefficient according to RelationshipEquation.

T(λ)=exp(−α(λ)d)=exp(−4/λ×k(λ)d)  [Relationship Equation]

In Relationship Equation, T(λ) indicates transmittance depending on awavelength, A indicates a wavelength (unit: nm), k(λ) indicates anextinction coefficient depending on a wavelength, and d indicates a filmthickness (unit: nm).

The refractive index and the extinction coefficient are obtained from apolarized light characteristic change (Delta, Psi) by using anEllipsometry equipment (J.A.Woollam Co.). Herein, the extinctioncoefficient obtained from Ellipsometry turns out to correspond with anextinction coefficient obtained from Relationship Equation 1.

The results are shown in Table 1.

TABLE 1 Average refractive Average extinction index (n) coefficient (k)(@900-1000 nm) (@900-1000 nm) Preparation Example 1 1.49 0.06Preparation Example 2 1.49 0.11 Preparation Example 3 1.49 0.17Preparation Example 4 1.49 0.22 Comparative Preparation 1.49 0 Example 1

Design and Evaluation I of Combination Structure

Based on the properties of the films, an optical simulation with respectto combination structures is performed by using a FDTD (Finite-differenttime domain, Lumerical Inc.).

Example 1

A combination structure is formed to have a structure of forming alight-absorbing layer and a TiO₂ nanostructure array in the same layeron a SiO₂ substrate (FIG. 4).

The light-absorbing layer is designed to be 250 nm thick based onproperties of the film according to Preparation Example 1.

The TiO₂ nanostructure array is obtained by designing a periodicalpattern of the following TiO₂ nanostructure (a refractive index: 2.5 @940 nm).

-   -   Shape: cylinder    -   Shape of cross-section: rectangular    -   Width (W₁ and W₂): 420 nm,    -   Thickness (t₁ and t₂): 250 nm,    -   First gap (g₁): 200 nm    -   Second gap (g₂): 160 nm    -   First period (p₁): 620 nm    -   Second period (p₂): 580 nm

Example 2

The same structure as that of Example 1 is formed except that thelight-absorbing layer is designed based on properties of the filmaccording to Preparation Example 2.

Example 3

The same structure as that of Example 1 is formed except that thelight-absorbing layer is designed based on properties of the filmaccording to Preparation Example 3.

Example 4

The same structure as that of Example 1 is formed except that thelight-absorbing layer is designed based on properties of the filmaccording to Preparation Example 4.

Example 5

The same structure as that of Example 1 is formed except that the TiO₂nanostructure array is designed to have the following periodical patternof the TiO₂ nanostructure.

-   -   Shape: cylinder    -   Shape of cross-section: rectangular    -   Width (W₁ and W₂): 420 nm,    -   Thickness (t₁ and t₂): 250 nm,    -   First gap (g₁): 180 nm    -   Second gap (g₂): 160 nm    -   First period (p₁): 600 nm    -   Second period (p₂): 580 nm

Example 6

The same structure as that of Example 1 is formed except that the TiO₂nanostructure array is designed to have the following periodical patternof the TiO₂ nanostructure.

-   -   Shape: cylinder    -   Shape of cross-section: rectangular    -   Width (W₁ and W₂): 420 nm,    -   Thickness (t₁ and t₂): 250 nm,    -   First gap (g₁): 220 nm    -   Second gap (g₂): 160 nm    -   First period (p₁): 640 nm    -   Second period (p₂): 580 nm

Reference Example 1

A structure is formed to have a 250 nm-thick light-absorbing layer on aSiO₂ base layer without the TiO₂ nanostructure array. Thelight-absorbing layer is designed based on properties of the filmaccording to Preparation Example 1.

Reference Example 2

A combination structure is designed to have the cycloolefin polymerlayer (no near-infrared absorbing compound) according to ComparativePreparation Example 1 and the TiO₂ nanostructure array in the same layeron a SiO₂ base layer (FIG. 4).

The cycloolefin polymer layer is designed to be 250 nm thick.

The TiO₂ nanostructure array is designed to have a periodical pattern ofthe TiO₂ nanostructure (a refractive index: 2.5 @940 nm) likewiseExample 1.

Reference Example 3

The same structure as Example 1 is formed except that the TiO₂nanostructure array is designed to have the following periodic patternof the TiO₂ nanostructure.

-   -   Shape: cylinder    -   Shape of cross-section: rectangular    -   Width (W₁ and W₂): 420 nm,    -   Thickness (t₁ and t₂): 250 nm,    -   First and second gaps (g₁ and g₂): 160 nm    -   First and second period (p₁ and p₂): 580 nm

Evaluation

Optical properties of the structures according to Examples and ReferenceExamples are evaluated.

The results are shown in Tables 2 and 3 and FIGS. 15 to 20.

FIG. 15 is a graph showing transmission spectra according to Examples 1to 4 and Reference Examples 1 and 2, FIG. 16 is a graph showingreflection spectra according to Example 1 to 4 and Reference Examples 1and 2, FIG. 17 is a graph showing absorption spectra according toExamples 1 to 4 and Reference Examples 1 and 2, FIG. 18 is a graphshowing transmission spectra according to Examples 1, 5, and 6 andReference Example 3, FIG. 19 is a graph showing reflection spectraaccording to Examples 1, 5, and 6 and Reference Example 3, and FIG. 20is a graph showing absorption spectra according to Examples 1, 5 and 6and Reference Example 3.

TABLE 2 Absorptance Transmittance Reflectance (@925 nm) (%) (@925 nm)(%) (@925 nm) (%) Example 1 64.6 14.6 20.8 Example 2 67.7 19.8 12.5Example 3 65.4 26.3 8.3 Example 4 63.1 29.4 7.5 Example 5 56.8 30.5 12.7Example 6 44.6 43.9 11.5 Reference 15.7 81.1 3.2 Example 1 Reference 0.331.2 68.5 Example 2 Reference 40.4 56.4 3.2 Example 3

TABLE 3 Wavelength Transmittance (%) width (nm) at local minimumTransmittance (%) at 50% point (Q₁ and at local maximum transmittanceQ₂) of peak point Q₃ of peak Example 1 54 24.9/12.8 30.4 Example 2 6731.7/20.1 32.1 Example 3 82 36.5/25.8 33.3 Example 4 99 27.7 (singlepeak) 37.0 Example 5 43  6.6 (single peak) 13.4 Example 6 65 27.3/17.947.1 Reference 34 0.99/2.73 43.1 Example 2 Reference 35 (single peak) —Example 3

Referring to Tables 2 and 3 and FIGS. 15 to 20, the structures accordingto Examples 1 to 6 exhibit improved light absorption characteristics ina relatively wide wavelength range due to complementary combination ofthe nanostructure array and the light-absorbing layer.

While this disclosure has been described in connection with what ispresently considered to be practical example embodiments, it is to beunderstood that the inventive concepts are not limited to theabove-described example embodiments. On the contrary, the inventiveconcepts are intended to cover various modifications and equivalentarrangements included within the spirit and scope of the appendedclaims.

What is claimed is:
 1. A combination structure, comprising: An in-planepattern of unit cells, wherein each unit cell of the unit cells includesnanostructures each having a dimension that is smaller than anear-infrared wavelength, and a light-absorbing layer adjacent to thenanostructures, the light-absorbing layer including a near-infraredabsorbing material configured to absorb light in at least a portion of anear-infrared wavelength spectrum, wherein the nanostructures define ananostructure array in the unit cells, and wherein a wavelength width at50% transmittance of a transmission spectrum in the near-infraredwavelength spectrum of the combination structure is wider than awavelength width at 50% transmittance of a transmission spectrum in thenear-infrared wavelength spectrum of the nanostructure array.
 2. Thecombination structure of claim 1, wherein the transmission spectrum inthe near-infrared wavelength spectrum of the nanostructure array has afirst local minimum point and a second local minimum point separatedfrom each other and a first local maximum point between the first localminimum point and the second local minimum point, and a differencebetween a transmittance at either the first local minimum point or thesecond local minimum point and a transmittance at the first localmaximum point is greater than about 30%.
 3. The combination structure ofclaim 2, wherein the transmission spectrum in the near-infraredwavelength spectrum of the combination structure has a third localminimum point and a fourth local minimum point separated from each otherand a second local maximum point between the third local minimum pointand the fourth local minimum point, and a difference between atransmittance at either the third local minimum point and the fourthlocal minimum point and a transmittance at the second local maximumpoint is smaller than the difference between the transmittance at eitherthe first local minimum point or the second local minimum point and thetransmittance at the first local maximum point.
 4. The combinationstructure of claim 3, wherein the difference between the transmittanceat either the third local minimum point and the fourth local minimumpoint and the transmittance at the second local maximum point is lessthan or equal to about 30%.
 5. The combination structure of claim 1,wherein the nanostructure array includes a parallel pattern of a firstnanostructure, a second nanostructure, and a third nanostructure, and amagnitude of a gap between the first nanostructure and the secondnanostructure differs from a magnitude of a gap between the secondnanostructure and the third nanostructure.
 6. The combination structureof claim 5, wherein the gap between the first nanostructure and thesecond nanostructure is about 1.05 times to about 5 times as large asthe gap between the second nanostructure and the third nanostructure. 7.The combination structure of claim 1, wherein the nanostructure arrayincludes a first nanostructure and a second nanostructure which areadjacent to each other, and a dimension of the first nanostructure isdifferent from a dimension of the second nanostructure.
 8. Thecombination structure of claim 7, wherein a width of the firstnanostructure is about 1.05 times to 5 times as large as a width of thesecond nanostructure.
 9. The combination structure of claim 7, wherein athickness of the first nanostructure is about 1.05 times to 5 times aslarge as a thickness of the second nanostructure.
 10. The combinationstructure of claim 1, wherein the unit cells include a first unit celland a second unit cell which are adjacent to each other, the first unitcell includes a first nanostructure and a second nanostructure, thesecond unit cell includes a third nanostructure and a fourthnanostructure, the first nanostructure, the second nanostructure, thethird nanostructure, and the fourth nanostructure define a linearsequence of nanostructures extending in one direction, and a magnitudeof a gap between the first nanostructure and the second nanostructurediffers from a magnitude of a gap between the second nanostructure andthe third nanostructure.
 11. The combination structure of claim 10,wherein the gap between the first nanostructure and the secondnanostructure is about 0.2 times to about 0.9 times as large as the gapbetween the second nanostructure and the third nanostructure, or about1.05 times to about 5 times as large as the gap between the secondnanostructure and the third nanostructure.
 12. The combination structureof claim 1, wherein the wavelength width at the 50% transmittance of thetransmission spectrum in the near-infrared wavelength spectrum of thecombination structure is about 1.2 times to about 5 times as large asthe wavelength width at the 50% transmittance of the transmissionspectrum in the near-infrared wavelength spectrum of the nanostructurearray.
 13. The combination structure of claim 1, wherein the wavelengthwidth at the 50% transmittance of the transmission spectrum in thenear-infrared wavelength spectrum of the combination structure is about40 nm to about 200 nm.
 14. The combination structure of claim 1, whereinthe light-absorbing layer is at at least one of a lower surface, anupper surface, and/or one or more side surfaces of one or morenanostructures of the nanostructures.
 15. The combination structure ofclaim 1, wherein the nanostructures are in contact with thelight-absorbing layer.
 16. The combination structure of claim 1, whereinthe near-infrared wavelength is in a range of greater than about 700 nmand less than or equal to about 1200 nm.
 17. The combination structureof claim 16, wherein the near-infrared wavelength is in a range of about890 nm to about 990 nm.
 18. The combination structure of claim 1,wherein the nanostructures each include a material having a refractiveindex at 940 nm of greater than or equal to about 2.0.
 19. Thecombination structure of claim 18, wherein the nanostructures eachinclude titanium oxide, silicon, aluminum, a Group III-V semiconductorcompound, or a combination thereof.
 20. The combination structure ofclaim 1, wherein a maximum absorption wavelength of the near-infraredabsorbing material is in a range of about 890 nm to about 990 nm. 21.The combination structure of claim 1, wherein a thickness of thecombination structure is less than or equal to about 1 μm.
 22. Acombination structure, comprising: an in-plane pattern of unit cells,wherein each unit cell of the unit cells includes two or morenanostructures each having a smaller dimension than a near-infraredwavelength, and a light-absorbing layer adjacent to at least one of alower surface, an upper surface, and/or one or more side surfaces of oneor more nanostructures of the two or more nanostructures, thelight-absorbing layer including a near-infrared absorbing materialconfigured to absorb light of at least a portion of a near-infraredwavelength spectrum, the unit cells include a first unit cell and asecond unit cell adjacent to each other, the first unit cell includes afirst nanostructure and a second nanostructure, the second unit cellincludes a third nanostructure and a fourth nanostructure, the firstnanostructure, second nanostructure, third nanostructure, and fourthnanostructure define a linear sequence of nanostructures extending inone direction, and wherein a dimension of the first nanostructure isdifferent from a dimension of the second nanostructure, or a magnitudeof a gap between the first nanostructure and the second nanostructure isdifferent from a magnitude of a gap between the second nanostructure andthe third nanostructure.
 23. The combination structure of claim 22,wherein the dimension of the first nanostructure is different from thedimension of the second nanostructure, and a width of the firstnanostructure is about 1.05 times to about 5 times as large as a widthof the second nanostructure.
 24. The combination structure of claim 22,wherein the gap between the first nanostructure and the secondnanostructure differs from the gap between the second nanostructure andthe third nanostructure, and the gap between the first nanostructure andthe second nanostructure is about 0.2 times to about 0.9 times as largeas the gap between the second nanostructure and the third nanostructure,or about 1.05 times to about 5 times as large as the gap between thesecond nanostructure and the third nanostructure.
 25. An optical filtercomprising the combination structure of claim
 1. 26. A camera comprisingthe optical filter of claim
 25. 27. An image sensor, comprising: asemiconductor substrate including a plurality of photodiodes, and anoptical filter on the semiconductor substrate and configured to blocklight in at least a portion of a near-infrared wavelength spectrum,wherein the optical filter includes the combination structure ofclaim
 1. 28. The image sensor of claim 27, further comprising a colorfilter on the optical filter.
 29. A camera comprising the image sensorof claim
 27. 30. An electronic device comprising the optical filter ofclaim
 25. 31. An electronic device comprising the camera of claim 26.32. An electronic device comprising the image sensor of claim 27.